OK so me and my ex just got done having sex for the third time, she has had her period and all the first 2 times after but this time I'm worried cause I put the condom on backwards (not all the way down but just barely on the tip) now I'm afraid she could get pregnant cause it might have ripped or the pre got on it, she says she literally just got off her period. Should I worry?

Yeah. Any time you have sex there's a chance of pregnancy.

I noticed you said you and your ex. What are you doing having sex with your ex? Are you ready to raise a child with her?

the condom was backwards-ish
It sounds more like the condom was not-quite-on-ish. Anytime -- yes, ANYtime -- you have sex, figure you will become a parent nine months later. Women have gotten pregnant while having their period, while holding their breath, while on two different kinds of birth control. Those naughty, wiggly little sperm just don't want to be stopped.

Now you two play the waiting game. Remember, if you don't want to be a daddy, don't have sex. (And no, you won't die if you don't have sex.)